The proposed five-year program is to foster the academic development of the applicant. Specific goals are: (1) To enhance the applicant's research skills that apply to the study of mental disorders in the elderly, particularly the clinical heterogeneity of Alzheimer's disease (AD); (2) To better his understanding of the phenomenology and neuropsychology of behavioral and cognitive disturbances in patients with AD; (3) To foster his development as a teacher and faculty resource in the areas of dementia and the neuropsychological aspects of mental disorders in the elderly. Plans proposed to achieve these goals are: 1. The applicant will implement two pilot studies to test the hypothesis that behavioral and cognitive heterogeneity in AD is associated with diffuse Lewy body (LB) pathology. As many as 60% of AD patients develop psychosis and other behavioral symptoms. Identifying a subtype associated with these symptoms will foster better treatment and increase our understanding of AD. Study 1) To validate new clinical diagnostic criteria for dementia associated with LB pathology, retrospective chart review will be carried out on deceased patients who were assessed for the presence of LB. Study 2) To test whether diffuse LB pathology is associated with greater damage to cholinergic systems, patients with and without possible diffuse LB pathology will enter a 4-week parallel-group, randomized, placebo controlled trial of a cholinesterase inhibitor (tacrine) to test for a differential response in sensitivity. 2. The applicant will pursue additional research training, participate in ongoing and future collaborative research projects, and consult with experts in geriatric mental health research. 3. He will complete additional training in behavioral statistics and will assume important responsibilities in the Department of Psychiatry and Behavioral Sciences at USC. 4. He will share his knowledge of the neurobiological aspects of mental disorders in the elderly with clinical psychology interns, clinical psychology graduate students, medical students, physician-trainees, and fellow faculty at USC.